Originally published in 1914, this volume was created to mark the tercentenary of John Napier's Mirifici Logarithmorum Canonis Descriptio. Written by the prominent English mathematician Ernest William Hobson, the text provides a highly readable introduction to the theory of logarithms and puts their discovery within a historical context. Illustrations are also included. This is a concise and accessible book that will be of value to anyone with an interest in logarithms and the history of mathematics.